SA200 hex barrel won’t strike an arc

By Jallen2275 Date 07-27-2018 18:49

I have ran into a problem with my sa200. We can’t get it to arc even when we try to strike the negative directly. It just creates a few sparkles and won’t idle up. The aux outlet will run a grinder just fine and I’m getting 100V at the outlet when I idle it up manually. Even manually idling the machine up it won’t strike an arc. I have 180 ohms when I test the exciter coils and get .5 ohms on my highest range with one lead on the armature and the other on the ground screw. I’ve checked the wiring and cleaned the ground post and most of the connections on everything. My meter shows the resistance to work like normal on the rheostat, they go up and down fairly smooth when I turn the dial. I’ve checked the 2 exciter brushes and the 6 main brushes to make sure they are free and still have life left. When I test the resistance between the brown and blue wires that run into the stator housing I have .3 ohms with my meter on the highest range, 2M. I also am getting about 3 volts where the welding leads connect to the machine with it on high idle. Any suggestions as to what exactly I need to look for in order to determine what needs replaced would be greatly appreciated. Thanks.

By psnort

Date 07-27-2018 21:09

Check for a damaged or stuck brush, or for a brush that has worn to the end of its' throw. A stuck brush on the main generator can produce the conditions you describe. You may need to clean (sand or stone) the commutator rings also.

By Jallen2275 Date 07-27-2018 21:45

When you say commutator rings what are you referring to? The copper looking bars on the armature?

By psnort

Date 07-28-2018 22:04 Edited 07-28-2018 22:08

Yes. The surfaces the brushes ride on. I have a stone I got from the Lincoln dealer many years ago which is very good. I have used sandpaper when I don't have the stone with me. This is done with the machine running. Careful. Not for the faint of heart. Copper bars should be shiny, smooth and even when you are done. Check to see that the brushes move freely in their slide tubes and that the springs are functioning as they should. Stuck brush is a common problem on these old machines. The surface of the brush that bears on the commutator should be smooth, undamaged and shaped to fit against the commutator. When the brushes wear down they will run out of travel and cease to function. It only takes one stuck or worn out brush and no welding today. When I do this I do both the main generator and the exciter, although the problem is usually with the generator. Put the brush cover back in place after to keep water, dirt and dust away from the commutator/brushes. Both brush covers.

By Jallen2275 Date 07-31-2018 00:31

I haven’t had any luck with this. I cleaned the main armature today with sandpaper and checked the brushes and they move freely. I’m still just getting sparkles and no arc. Any other ideas as to what I could check to figure out what I should replace?

By Jallen2275 Date 07-31-2018 00:34

If it means anything I’ve noticed that the brushes in the main armature don’t spark but the brushes on the exciter armature do.